c++编程时为什么老是出现cout未定义

2024-11-29 16:18:43
推荐回答(3个)
回答1:

#include
using namespace std; //加上这句

cout输出流类声明和定义都在iostream之中(对于非标准C++而言是iostream.h)其名字位于std空间,对于某些编译器,特别是针对Windows平台的开发工具,都要显式声明命名空间。

cout是输出函数 std是命名空间, std::out表示,out函数属于std这个命名空间,std就相当于C当中的stdio.h但他们有本质的区别,只能说是相当于。std命名空间下的cout方法,要是你写using namespace std;就不用写std::直接cout、

回答2:

你在包含头文件的地方添加
#include
using namespace std;
试试。

将上面两句拿到你定义类的文件的上面去。
如下:
#include
#include
using namespace std;

class myclass
{
private:
int x,y;
public:
myclass (int x=0,int y=0)
{
this->x=x;this->y=y;
}

void print ()
{
cout<<"x=:"<}
~myclass ()
{
cout<<"hello"<}
};
int main(void)
{
myclass my1,my2(3,4);
cout<<"my1:";
my1.print();
cout<<"my2:"; my2.print();
}

回答3:

你有#include吗?cout << 是在iostream 库中的

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